i think again and again Rizzo shows he won't pay a lot for free agents, Werth as the exception, he prefers to fill voids through trades, and for position players - he values defense above all else.
If we swing something for Shields, I'd bet on Morse for Shields straight-up, or maybe he'll throw in a AA/A prospect like Kobernus. With Shields only having two years left, I don't think he'll give up much. It would be crazy to part with Espinosa for two years of Shields.
You don't really think Morse would bring back Shields, do you???? We'd be lucky to get a reliever for Morse.